Fuel distribution system for hightemperature pebble bed furnaces



F. M. WOLF 2,408,282 FUEL DISTRIBUTION SYSTEM FOR IIIGH-TEMPERATURE PEBBLE BED FURNACES Sept. 24, 1946.

Filed July 11,; 1944- 2 Sheets-Sheet 1 A I W I l l I I I l l l I l l I I I l I 1 I I Sept. 24,-1946. F. M. WOLF 2,408,282

DISTRIBUTION SYSTEM FOR HIGH-TEMPERATURE PEBBLE BED FURNACES Filed Jul 11, 1944 2 Sheets-Sheet 2 Patented Sept. 24, 1946 FUEL DISTRIBUTION SYSTEM FOR HIGH- TEMPERATURE PEBBLE BED FURNACES Frank M. Wolf, Madison, Wis., assignor to Wisconsin Alumni Research Foundation, Madison, Wis., a corporation of Wisconsin Application July 11, 1944 Serial No.'544,446 M 6 Claims. (01. 23-277) This invention relates to an improved means for delivering fluid fuel under pressure to a high temperature locus within a high-temperature furnace of the pebble bed type. embodiment it resides in an improved fluid fuel inlet member for a gas reaction furnace of .the type described and claimed in U. S. application Serial No. 498,896, filed August 16, 1943, by Farrington Daniels and William G. Hendrickson jointly with the present applicant. Reference also'is made to application Serial No. 549,705, filed August 16, 1944, by Farrington Daniels and William G. Hendrickson, and to application Serial No. 538,898, filed June 6, 1944,.by Farrington Daniels.

In the type of gas reaction furnace just referred to two pebble beds (for preheating a combustionsupporting gas to be reacted and for chilling gaseous reaction products and simultaneously conserving heat from the latter) are positioned one above the other in a tubular, thermally insulated vessel, the two pebble beds being separated by a gas-mixing and combustion space provided by the interstices in a body of refractory objects all of which objects are larger than the pebbles constituting said pebble beds and some at least of which are of a size too large to function acceptably as means for the quick interchange of heat but sufficiently large to provide desirably large interstitial spaces for gas mixing and for gas reactions. The gas to be reacted is caused to move through the furnace in such direction that it is preheated by abstraction of heat from the pebbles of the first pebble bed, is passed through the centrally disposed gas-mixing and combustion space, and thence is passed through the second of said pebble beds. For maintaining a predetermined high temperature within said gasmixing and combustion space, fluid (e. g., gaseous) fuel under pressure is led thereto by means of In its preferred water-jacketed fuel inlets which project from the outer (cool) ends of said pebble beds axially v space, their inner ends dischargingthe fluid fuel in a direction parallel to the major axis of the furnace and hence parallel to the direction of movement of the combustion supporting gas to be reacted in said furnace." The so-discharged fuel, in the aforesaid centrally disposed space, is (1) mixed with the gas to be reacted by the progressive mingling of said fuel and said gas 00- casioned by the repeated mutual deflection of the streams of fuel and gas by the refractory objects filling said space, and (2) burned in said space.

' Because the mixing of the parallel streams of fuel and gas, in the system above described, is a gradual and progressive operation, the axial dimensions of the gas-mixing and combustion space of the furnace has to be made relatively long, e. g., considerably longer than that of either of said pebble beds, in order to insure that thorough mixing and the combustion of the fuel are effected before fuel and gas pass into the second of'the pebble beds. Moreover, it'has been thought necessary to macadami'ze the assemblage of relatively large refractory objects which fill the gas-mixing and combustion space and to insure that at least a part-of the macadamized assemblage was constituted by refractory objects of relatively large size (e. g., 5" or 6" chunks). The fuel-inlet member constituting the present invention. divides the fuel supply (which, as brought into the furnace and as passed through the pebble bed, is initially'a single fuel stream having" a direction parallel to the major axis of the furnace) into a plurality of smaller streams, and discharges these small fuel streams laterally of the member, that is to say, it discharges the "divided fuel streams in directions initially transverse to'the direction'of movementof the gasto be reacted; The initial fuel stream is thermally insulated by 'fluid, coolant during its entire course through the pebble bed, and the ensuing divided" fuel streams similarly ar thermally insulated until they are ejected from the-memher. When the fuel being employed is gaseous, as usually obtains, the initial stream thereof is given an annular shape and is thermally insulated by means of a central stream of coolant Within the fuel stream annulus and an annular stream of the coolant surrounding the fuel stream annulus.

In its preferred embodiment, the fuel inlet member of th present invention comprises three spaced concentric tubular members, e. g., metal .pipes, extending from outside an end of the furnace through a portion of the pebble bed filling and to a high-temperature locus therein, the inner ends of the innermost and intermediate pipes being joined to close off .the inner end of the annular space therebetween, a metallic member closing the inner end of the outermost pipe and spaced from the joined ends of th innermost and intermediate pipes to provide therebetween a passageway communicating between the interior of innermost pipe and the space between the intermediate and outermost pipes, a plurality of nipples radially extending through the walls of the intermediate and outmost pipes adjacent their inner ends to provide a plurality of discharge passageways from the space between the innermost and intermediate pipes, means for introducing a fluid coolant into the outer end of said innermost pipe, means remote'from the furnace for introducing a fluid fuel into the space between the innermost and intermediate pipes, and means for withdrawing fluid coolant from the outer end of the space between the intermediate and outermost pipes.

When a gaseous fuel and a, liquid fuel are to be employed alternately, the fuel inlet member just described is modified by the provision of an axially disposed liquid fuel conduit terminating at its inner end in a plurality of lateral branches so designed as to discharge liquid fuel through the same fuel-ejecting elements employed for ejecting the gaseous fuel: in such event, the fuelejecting elements desirably may be tapered toward their exit ends.

By reason of the subdivision of the initial fuel supply stream into a, plurality of smaller streams, and by reason of the lateral (e. g. radial) directions of the smaller fuel streams at discharge, it follows that the fuel is more quickly mixed with the gas to be reacted, and is burned, much earlier in the course of the travel of the latter through the gas-mixing and combustion space than obtains in the case of the hereinbefore-described system; this circumstance makes it possible to shorten materially the gas-mixing and combusgtionspace and hence the over-all axial dimension of the furnace, thereby saving heat by diminishing the amount of heat radiated through the tuublar wall of the furnace at the hottest zone of the latter and of course effecting a saving of the expensive filling material necessarily used in forming the central portion of the shaft filling. In the operation of the system of the present invention the fuel may be caused to burn in a relatively fiat zone normal to the direction of movement of the gas to be reacted (i. e., to provide a sharp line of combustion just-above the mixing zone). Also, by reason of the very prompt mixing of the fuel with the gas, the cracking of thermally unstable fuel-with resulting deposition of solid carbon and creation of local hotspots-is minimized or even eliminated.

Other advantages accruing from use of the present system include the following:

(a) the inner ends of the fuel inlet members being closed (from the standpoint of the major axis), pebbles cannot work into their ends to close off the fuel supply orifices;

(b) combustion space refractory objects or pebbles may be smaller (say, 2" to 3") (than heretofore used (e. g., 6") because mixing of fuel and air is more positively promoted;

(0) using smaller pebbles in the combustion space gives larger surface area per cubic foot of the filling material, and hence permits burning more fuel completely (e. g., surface combustion effect).

The fuel inlet members may and preferably do discharge into a mass of relatively large refractory pebbles or pebble-like objects providing relatively large interstices. These large objects may be in a generally horizontally disposed layer within the shaft filling. While the upper and lower surfaces of said layer may be parallel planes, either surface thereof may be a convex surface having its nearest approach to the other adjacent said fuel inlet device. In this latter event,

the "angularity of the convex surface may correspond to the resultant of two opposing forces, viz., the force of the air current passing axially through the bed and the force of the fuel gas streams normal thereto.

The jet velocity of the discharged fuel gas may be varied, as desired, without a corresponding change in the calories introduced per unit of time, either (a) by suitable choice of cross sectional area of the discharge orifices, thereby providing a. desired jet velocity, or (b) by diluting the fuel gas with air or an inert gas such as carbon dioxide and forcing an increased amount of the lower caloried mixture through the orifices per unit of time. In case (a), I prefer to give the inner surface of the orifice a conical shape (as indicated for element !9 of Fig. 4 of the accompanying drawings) as an expedient favoring high jet velocity of the gas discharged therethrough.

The invention will, in the following be described more particularly, and with reference to the accompanying drawings, in which Fig. 1 is a side elevational view, with parts in section, illustrating one embodiment of the invention;

Fig. 2 is a side elevational view, with parts broken away, illustrating a preferred mode of assembling the device as illustrated in Fig. 1;

Fig. 3 is a fragmentary side elevational view of the upper portion of the device as shown in Fig. 1, and illustrating a detail of construction of the latter;

Fig. 4 is a view similar to Fig. 1 but illustrating a modification in which fuel oil may be employed as the fuel as an alternative for gaseous fuel;

Figs. 5 and 6 are perspective views of two forms of nozzles or tips suitable for use in the modification shown in Fig. 4; and

Fig. 7 is an elevational View showing the device of the present invention in operative relationship to the pebble bed of a pebble bed furnace.

In the device illustrated in Fig. l, l, 2 and 3 are three concentric pipes spaced to provide passageways 4 (between outermost pipe l and intermediate pipe 2) and 5 (between intermediate pipe 2 and innermost pipe 3) for fluids. The top end of pipe I extends somewhat above the top ends of pipes 2 and 3, and its bottom end terminates short of the bottom end of pipe 2. The threaded bottom end of pipe 3 extends for a considerable distance below the bottom end of pipe 2. Pipes 3 and 2 are secured together at their tops and at the bottom of pipe 2, and the space between said ends closed. off, by filler metal members e and 1, respectively. A cover member 8 is secured to the upper end of pipe I, said cover member being sufficiently spaced from the ends of pipes 2 and 3 to leave therebetween a fluids passageway communicating between the interior of pipe 3 and the space between pipes 2 and At the bottom end of pipe I this latter is secured to pipe 2 through, and the space between them is closed off by, filler member IE5.

Egress of fluid from the top of the space 5 between pipes 3 and 2 is provided by a plurality of (e. g., four) nipples 9, 9, communicating with the space 5 through openings in the walls of pipes i and 2. Said nipples serve also to hold the tops of pipes l and 2 rigidly in position with respect to each other. Access of fluid to the bottom of said space is provided by an outstanding threaded nipple i6 communicating with space 5 through an opening in the wall of pipe 2. Egress of fluid 5 from the bottom of space 4 is provided by an outstanding threaded nipple l I communicating with space 4 through an opening in the wall of pipe i.

The complete fluid fuel-introducing device, D, has a length, between outstanding nipple H and nipples 9, 9 such that the upper portion of the device may, as shown in Fig. 7,project, with nipples l and II exposed (accessible), within a pebble bed furnace through a substantial part of a pebble bed and to a locus whereat delivery of fuel gas is desired. .Since the depths of such pebblebedare, in turn, determined by a numberiof variable factors, it is impossible'arbitrarily to-as-sig'n any specificlength value with respect to the device: however, it may be noted that the specific device shown in Fig. 7 has a length of approximately 18 inches between nipples 9 and nipple H, and is adapted to project through a grating 4 l, 42, of about 1 inch and through a pebble bed, Zone F1, of approximately 12 inches depth supported on said grate.

Fig. 7, which is not drawn to scale, shows a pair of the fuel inlet devices of the present invention installed in a specific construction of a pebble bed furnace for fixing atmospheric nitrogen. In Fig. 7, F1, F2 and'Fs taken together represent a shaft filling enclosed within a tubular refractory wall 30, which latter is supported upon a base 3| of heat-resistant concrete. 32 is an outer shell of sheet iron concentrically surrounding and spaced fromtubular wall 30, the so providedspace being filled with a mass of loose unclassified magnesia insulation 33 supported on base 3|. 34 is a centrally domed cover secured along its periphery to the upper edge of shell 32. Cover 34 rests upon the upper end of tubular wall 30, and its domed portion rises above the space enclosed by said wall, providing an open space 3? above the shaft filling. A functionally similar open space 31' is provided in base 3! beneath said shaft filling. The opening 37 in base 3| is bridged at its topby spaced grate bars 41 supporting a water-cooled 2 this latter is a coiled iron pipe whose inlet and outlet connections (not shown) pass through base space 31 and base 3! to the outside.

The shaft filling F1, F2, F3 is supported upon said bars 4| and water-cooled grate 42.

Zone F1 of the shaft filling is composed of a relatively thin layer 43 of refractory pebbles of about l /z-inch size, adjacent bars M and grate 42 and, superposed thereon, a bed 44 of refractory pebbles of smaller size, e. g., 34 mesh Tyler screen. The layer 43 of somewhat larger refractory pebbles serves to prevent gravitational escape of the smaller pebbles constituting bed 44 through grate 42 and bars 4 I.

Zone F2 is a relatively tall column of relatively large refractory bodies, e. g., fused magnesia V chunks, ranging in size from /2 inch to 5 inches As shown in the drawings, 7

average diameter. the refractory bodies are disposed inlayers according to their sizes, the largest chunks occupy-. ingthe functionally central part ofthe column and flanked below and above by successive layers of refractory bodies of progressively smaller sizes.

Zone F3 is identical with zone Fi'but inverted. Zones F1 and F3 constitute'the hereinbeforereferred to pebble beds for preheating a gas to be thermally reacted and tion products, while zone F2 constitutes the gas.- mixingand combustion space Fluid fuel-introducing device D i positioned partly within open space 37 and partly in the lower portion of the shaft filling; it extends through bars 4! and grate 42 and zone F1 of the for chilling gaseous reac- 2 through device shown in'Fig. 7 a

B diagrammatically represents an air compressor to the pressure side of which is connected a reversing mechanism R. 38 and 33' are air conduits communicating between open spaces 37 and 31, respectively, and said reversing mechani'sm E. This latter mechanism is-connected to a nitric oxide recovery system (not shown).

When the deviceis in position in apebble bed furnace, as illustrated in Fig. 7, with its major axis parallel to the major axis of the furnace,

the bottom threaded" end of pipe 3 is connected e of water (or other fluid coolant) underpressure. Nipple H may be connected to'any suitable means for disposing of coolant, e. g., to a cooling water spray tower for dissipating heat from the cooling water incident to return of the water to pipe 3 of 'the'device. Nipple I9 is connectedto a suitable source of fuel as under pressure. In'use, the fluid coolant flows inwardly through pipe 3, thence into the space between the inner end of pipe 3 and cover member 8, thence outwardly through the space 4, and discharges throughnipple ll. Fuel gas is admitted into spacel5 of the device by nipple l0 and flows inwardly through said space; at the inner end of said space, the stream of fuel gas is divided into a plurality of smaller streams which are discharged through nipples 9, 9 radially into the pebble bed F2 in directions initially normal to the direction of movement of the gas being treated in said furnace.

In the use of the assemblage above described, with the setting of reversing mechanism R as current of air under pressure is forced, through conduit 38 and open space 31 into and upwardly through the shaft filling F1, F2, F3 and thence through open spacetl', conduit 38' and reversing mechanism R to a nitric to a suitable sourc oxide recovery system or to stack. Simultane-' ously,, by proper adjustment of valve V a stream of fuel gas is forced through pipe 39 to device D which latter subdivides thestream into a plurality of smaller streams which are radially emitted through members 9, 9 into the lower part of zone F2. Upon reversal of the air current direction, valve V is so adjusted as to stop flow of fuel gas D and to cause flow of fuel gas through device 1).

Fig; 2 shows an intermediate stage in the preferred mode of constructing the device shown in Fig. 1.

Openings I2 and 13 are provided in pipes I and' 2, respe ctively, :said openings being so located, adjacent the ends of the pipesthat, when the pipes are assembled in the posi tion'shown in Fig.2, the openings ment, with the end of pipe I extending somewhat beyond the end of pipe 2. Nipples 9, 9 are then welded to pipe 2 with their bores coinciding with openings l3. The top portion of pipe I is severed along a plane passing through the centers of openings I2. Pipe 3 isinsertedin pipe 2, their ends are spaced'byfiller members 6 and 1, and the pipe ends and filler members are unitedby I2 and I3 ,will be in align welding; The resulting; assembly of pipes 3 and 2, with nipples 9, 9 attached to the latter, is inserted in pipe through the upper end thereof and with nipples 9, 9 resting in the lower halves of openings l2. The cover member 8 is secured at the top of the severed top portion of pipe 1 by welding. The resulting closed end portion is placed in position over pipe 1' and reunited'to the latter by welding, and nipples 9, 9 are secured to the thus-reunited pipe I by welding, as indicated in Fig. 3, thus completing the discharge end of the device.

Nipple II is secured by welding to pipe I in communication'with the opening l4 provided in said pipe. Nipple I9 is secured by welding to pipe 2 in communication with. the opening provided in pipe 2. The space between the lower end of pipe I and the outer wall of pipe 2 is then closedby welding in filler member 16.

The device illustrated in Fig. 4 is generally similar to that shown in Fig. 1: it differs from the latter in the following structural respects: Within pipe 3 there is positioned a pipe I! for leading liquid fuel (e. g., fuel oil) inwardly to-the plane of fuel gas discharge from space 5. Pipe l1 terminates at its inner end in a plurality (e. g., four as shown) of laterally oifstanding branch conduits l8, l3: these latter extend through openings provided in, and are secured to, pipe 3 and substantially across space 5, with their outer, open ends in axial alignment with the fuel gas discharge means from space 5. These latter, elements I9, 19, differ from the nipples 9, 9 of Fig. 1 in that their bores aresubstantially conical with the bases. adjacent pipe 2. Elements l9, l9 are shown as having substantially cylindrical outer surfaces: however, they may, as is indicated in Fig. 6, be given. a streamlined contour in the direction of flow of. the coolant in order to minimize turbulence in the coolant stream immediately beneath said fuel gas discharge means. Pipe Il may, as shown, be introduced into the lower end of the device through the packing gland 29 in elbow H at the end of pipe 3.

In the operation. of the modified device of Fig. 4, gaseous fuel, only, is used during an initial stage of heating of the pebble bed, after which thefeeding of fuel gas is stopped and the feeding of fuel oil iscommenced. During the feeding of fuel oil to the device, a stream of air simultaneously is fed through nipple Hi into space him the purpose of forming an oil-air mixture for ejection from members l9, l9.

While the preferred form of the fuel inlet memher is such. that theincoming stream of coolant is enclosed by an annular stream of fuel and the latter in turn is enclosed by an annular stream of outgoing, coolant, the structure is operable when so modified that fuel is introduced through the innermost pipe, the. incoming stream of coolant is introduced through the space between the innermost and intermediate pipes, and the outgoing stream of coolant makes use of the space beween the intermediate and outermost pipes. In such event the lateral branches or nipples for discharging fuel extend, through the walls of at least the innermost and outermost pipes, and communication between the inner end of the space between the innermost and. intermediate pipes and the inner end of the space between. the intermediate and outermost pipes is provided. Such communication. desirably may be provided by terminating the inner end of the intermediate pipe short ofthose of the innermost and outermost pipes.

The side wall and/or the inner. endwall of the fuel inlet member may, if desired, bev provided with an outer covering of suitable heat-insulating material for protecting the metal of the member.

The fuel inlet device of the present invention is particularly. adapted for use in the following modification of the conventional operation of the nitric oxide furnace: The fuel inlet device and the layer of large refractory chunks into which it discharges are substantially axially centrally located within the shaft filling. During one-half of the complete cycle a current of air is passed upwardly through the shaft filling, while. during the succeeding one-half cycle a current of air is passed downwardly through the shaft filling. Fuel gas is discharged through the fuel inlet device for a part, only, of each half cycle, in a total amount suitable to maintain the central portion of the shaft filling at a predetermined temperature, in the following manner: In a sit.- uation wherein a complete cycle (upstroke. plus downstroke) is of 20 minutes duration and wherein it is necessary to burn fuel gas for six-tenths of the total time, the fuel gas may be admitted during the last 6 minutes of one stroke and for the first 6 minutes. of the next succeeding stroke, the fuel as being turned off for the beginning 4 minutes of the first-mentioned stroke and likewise for the final 4 minutes of the second-mentioned stroke. The furnace system can be so arranged that during the 12 minute period of each complete cycle in which fuel gas is being introduced and burned the gases simultaneously being discharged from the furnace are either wasted to stack or are diverted to' a secondary recovery system, while during the other 8 minute period of the cycle the gases discharged from the furnace are, conveyed to the primary recovery system for recovery therefrom. of their proportionally larger content of oxide of nitrogen. It is to be understood, of course, that the above 12 to 8 ratio. is given by way of illustration only, and that the ratio of fuel gas on time to the fuel gas off time in the complete cycle is adjusted to suit the particular furnace and the conduct of the process therein. In a case where heat losses are relatively low, the ratio may be as low as 3 (or even 2) to 5.

I claim.

1. A furnace of the pebble bed type comprising a tubular shaft, a supporting grating, a stratified series of transverse beds of refractory filling, said series including a centrally disposed bed of relatively large refractory objects and beds immediately above and below the said centrally disposed bed of relatively small refractory objects, said shaft and filling being so constructed and arranged as to provide open'. spaces above said filling and below said grate, reversible means for alternately directing gases to traverse said shaft into said spaces, reversible: means arranged to alternately feed fluid fuel to the top and bottom of said centrally disposed bed, and fuel feeding means in said. furnace comprising a fuel conduit extending from one of said. open spaces to said central bed, a plurality of laterally extending nozzles communicating with said tubular conduit, 2. fiuid coolant jacket surrounding said fuel conduit, and outlet means for said coolant arranged for extension to the exterior of the furnace.

2. A furnace of the pebble bed type comprising a tubular shaft, a supporting grating, a stratified series of transverse gas-traversable beds of refractory filling, said serie including a .9 centrally disposed bed of relatively large refractory objects and beds immediately above and. below the said centrally disposed bed of relatively small refractory objects, said shaft and filling being so constructed and arranged as to provide open spaces above said filling and below said grate, reversible means for alternately directing gases to traverse said shaft into said spaces, reversible means arranged to alternately feed fluid fuel to the top and bottom of said centrallydisposed bed, and a plurality of fuel feeding means in said furnace each fuel feeding means comprising a fuel conduit extending from one of said open spaces to said central bed, a

' plurality of laterally extending nozzles communicating with said tubular conduit, a fluid coolant inlet conduit inside said fluid fuel conduit, a fluid coolant jacket surrounding said fuel conduit, and in communication with said inner fluid coolant conduit at that end of the latter which is extended within the furnace, and inlet and outlet means for said coolant arranged for extension to the exterior of the furnace.

3. A furnace of the pebble bed type comprising a tubular shaft, a supporting grating, a stratified series of transverse gas-traversable beds of refractory filling, saidrseries including a centrally disposed bed of relatively large refractory objects and beds immediately above and below the said centrally disposed bed of relatively small refractory objects, said shaft and filling being so constructed and arranged as to provide open spaces above said filling and below said grate, reversible means for alternately directing gases to traverse said shaft into said spaces, reversible means arranged to alternately feed fluid fuel to the top and bottom of said centrally disposed bed and a plurality of fuel feeding means in said furnace each fuel feeding means comprising a gaseous fuel conduit extending from one of said open spaces to said central bed, a plurality of lateral gaseous fuel jets communicating with said gaseous fuel conduit, a fluid coolant intake conduit inside of said gaseous fuel conduit, a fluid coolant jacket surrounding said gaseous fuel conduit, and in communication with said inner fluid coolant conduit at that end of the latter which is extended within the furnace, a liquid fuel conduit within said fluid coolant intake conduit, a plurality of laterally otfstanding open ended branches extending from the inner end of said liquid fuel conduit through the fluid coolant intake conduit and into discharging proximity to said jets, and

10 inlet and outlet means for said coolant arranged for extension to the exterior of the furnace.

4. A fuel inlet device, comprising three concentric tubular members, of which the outer tubular member has a closure member at one end and is sealed to the intermediate tubular member at the other end, and of which the intermediate and innermost members extend short of the closure member and are sealed together at such end and also at the end of the intermediate member so as to form' an annular space with no communication to the innermost space'or to the space between the outer and intermediate tubular members, a plurality of passage members radially extending from adjacent the end of the intermediate tubular member near the closure member from the intermediate tubular member and the annular space between the innermost and intermediate tubesthrough the outermost tube to provide nozzle passage through said-space to the exterior, said uter tube being provided with an opening adjacent that end of said tube removed from the closure end, said intermediate tube being provided with an opening also adjacent the end removed from the closure member, and that end of the innermost tube which is removed from said closure member being open for connection to a source of coolant.

5. The fuel inlet device defined in claim 4, characterized in that a liquid fuel conduit is positioned within and spaced from the walls of the innermost tubular member, which liquid fuel conduit extends short of said closure member and terminates in a plurality of laterally olfstanding open-ended branches extending through the innermost tubular member and into discharging proximity to said radially extending passage members, there bein as many branches as there are passage members.

6. The fuel inlet device defined in claim 4, characterized in that said radially ext nding passage members are frustro-conical with the frustrated apices adjacent the outer tubular member, and in that a liquid fuel conduit is positioned within and spaced from the Walls of the innermost tubular member, which liquid fuel conduit extends short of said closure member and terminates in a plurality of laterally olf- ,standing branches extending through the innermost tubular member and into discharging proximity to said radially extending passage members and terminating in jet orifices, there being as many branches as there are passage members.

FRANK M. WOLF. 

